Ultrasound monitoring of a novel microwave ablation (MWA) device in porcine liver: lessons learned and phenomena observed on ablative effects near major intrahepatic vessels.
BACKGROUND
Microwave ablation (MWA) is postulated to have several advantages over other thermoablative modalities in the treatment of hepatic tumors. Herein, we use an in vivo porcine model to determine the effect of hepatic blood flow on a novel MWA applicator.


METHODS
Four 100-kg pigs underwent hepatic MWA (2,450 MHz, 100 W, 4 min) using a 5.7-mm diameter applicator (Microsulis Americas, Sulis V) inserted near large intrahepatic blood vessels. Real-time monitoring was performed using 3, 5, and 12 MHz diagnostic ultrasound transducers. The ablated zones were sectioned for gross and histological processing.


RESULTS
Ablation zones were uniform in shape and size (3-4 cm) and related to power deliver only. Gross and microscopic examination revealed direct extension of ablation zones to the margin of major hepatic blood vessels and occasionally beyond the intended target. Of note, a momentary acoustic white-out occurred around the probe at 25 +/- -1 s in every ablation.


CONCLUSIONS
The Sulis V MWA applicator produced uniform zones of ablation that remain unaffected by convective heat loss. The applicator induced a reproducible but temporary event as seen by ultrasound. Further study is warranted to define the physics, benefits, limits, and clinical safety of this new MWA technology.
Garrean
S
S
Department of Surgery, University of Illinois at Chicago, Chicago, IL, USA.
Hering
J
J
Saied
A
A
Hoopes
P J
PJ
Helton
W S
WS
Ryan
T P
TP
Espat
N J
NJ
D000818:Animals; D017115:Catheter Ablation / Q000295:instrumentation*; D006499:Hepatic Artery / Q000000981:diagnostic imaging / Q000473:pathology / Q000528:radiation effects*; D006503:Hepatic Veins / Q000000981:diagnostic imaging / Q000473:pathology / Q000528:radiation effects*; D008099:Liver / Q000000981:diagnostic imaging / Q000473:pathology / Q000528:radiation effects*; D008102:Liver Circulation / Q000528:radiation effects*; D008872:Microwaves; D023421:Models, Animal; D016343:Monitoring, Intraoperative; D012815:Signal Processing, Computer-Assisted; D013552:Swine; D014463:Ultrasonography